Maduramicin is a new antibiotic that has been shown to be an effective anticoccidial agent. Its preparation and use are described in U.S. Pat. Nos. 4,278,663; 4,368,265; and 4,407,946.
Animal feedstuff compositions containing a therapeutic and/or prophylactic level of maduramicin may be readily prepared by admixing the drug or a salt thereof with the feedstuff directly or by admixing a premix containing the drug with the desired feedstuff. Feed premixes are normally prepared by admixing the drug or salt thereof, or a solution of the drug or a salt thereof with an edible substrate such as corn cob grits, soybean feed, corn meal or the like. Application for U.S. patent application Ser. No. 641,094 filed Aug. 18, 1984, incorporated herein by reference, describes the use of physiologically acceptable alcohols as solvents for the preparation of animal premix compositions containing manduramicin.
Unfortunately it has been observed that the stability of maduramicin and salts thereof at elevated temperatures in feed premix compositions is reduced when premixes are prepared with certain edible carriers.
It is an object of this invention to provide a method for preparing feed premix compositions containing maduramicin and salts thereof which have improved stability at both elevated temperatures and ambient temperatures over extended periods of time.